1. The A story: about Zombies.
Answers: SPARROWHAWK, STEPS, SABRETOOTHTIGER, SMAUG, QATAR.

The B story: in the museum.
Answers: AUSTRIA, JAMESWATT, QUARTZ, MONGOLIA, JOHNCONNOR.

The C story: searching for Carol.
Answers: MACQUARIE, SNAIL, BANJO, SONNY, ZENITH.

The D story: following suspect/Bird Flu.
Answers: ORION, UMBRELLA, SALAMANDER, ENGAGED, MARKUS.

2. The A story: A4
Aha! A flash of insight comes to you as you study the solutions to the last two puzzles. .....Ten minutes later,...
you come to a plaza area containing the statue you were thinking of.
The previous solutions were STEPS and SABRETOOTHTIGER.

A1 starts in a city park. I don't know whether we are meant to try to find the location of this statue and the building with flagstone steps which the statue is facing.

Story B is based on a museum with wood-panelled walls, prehistoric dioramas, Neanderthal exhibit, one on ancient Egypt and then one on the Renaissance with Leonardo de Vinci.

Story C has photos of Carol in Sydney. C3
The clues so far lead you to believe Carol is referring to a construction site in the area. It is a controversial new shopping centre development...
Story D involves following the suspect. D2
...walking towards the seaside....near the aquarium and the ferry port ... plaque mounted onto the wall of a sandstone building.... the plaque is a war memorial.
D3
.. in the centre is a replica of Tutankhamun's burial mask. It looks like a museum exhibit. Of course! That's why the building had a war memorial on one wall.
Thinking of MUM's - maybe there are four recognizable locations which can be used to pinpoint a place which would be the answer.

3. That could be. The problem I see with that is you could solve the meta without knowing any of the answers (or at least most of them). That's typically frowned upon in puzzle hunts.

4. The solution:

A metapuzzle is one which is somehow distinct from the other puzzles in a competition. It may be presented in a different way, and may involve the other puzzles or their solutions in some way.

Our metapuzzle this year was rather sneaky, somewhat like last year's.
Just before the competition started, we changed the banner graphics and announced on the news page that we had done so. While our primary purpose was indeed to spruce up the graphics and add an Archive button, we had a surruptitious purpose too. We wanted to use it to add a metapuzzle to the competition!

Whenever a team solves an entire group of puzzles, they are rewarded with a medal graphic. A team who logs in can download large versions of the medals they have won. Those who did so would have noticed that on each there is a jigsaw puzzle piece with a letter within it.
Medal graphic Letter Group 1C Group 2I Group 3S Group 4R Group 5A
You don't need to download many of these graphics to guess that the puzzle pieces spell "CISRA" (the name of our company).

An intuitive leap can be made, that since each jigsaw puzzle piece is different and the puzzle pieces exist in the web site's banner, there could be a message spelled out in the banner. By assigning the known letters (C, I, S, R, A) to the matching jigsaw shapes in the banner, you quickly see the word "CISRA" spelled out. A flash of insight or a little bit of trial and error will reveal the encodings for other letters, which produce secret messages. Here's the whole banner decoded:

There are three secret sentences visible there. Near the middle, just below the large CISRA logo, it says:
CISRA PUZZLE COMPETITION
The key to decoding the puzzle pieces is realising that the word "CISRA" is followed immediately by "PUZZLE COMPETITION". Clues that may get you there are the double Z, the letter C, and the fact the red puzzle piece is the letter I, which visually matches the red letter I in the logo. This gives enough letters to decode the rest of the banner.
Reading down the left side of the banner is the word:
ENCORE
indicating that you are on the right track. But it's not the answer - no, that would be too easy . There are still two puzzle pieces visible in the banner but not yet decoded. After some trial and error, it becomes clear the missing pieces are a D and an H. Near the bottom it says:
REDO RAISE THAT HUNT CHUMP
This indicates that you need to try again, by hunting higher up in the banner.
Right at the top is the metapuzzle's secret sentence:
This is a reference to Citizen Kane, a movie in which on his death bed, the main character mourns his lost childhood by calling out the name of his beloved sled, ROSEBUD, the solution to our metapuzzle.

Incidentally, the large medal file names included a couple of semi-random words tacked on to the end. It was important to the metapuzzle that the file names of these medal graphics were not guessable, otherwise any team could obtain access to any large medal graphic by predicting the file names of medals they did not have. So we extended the obvious part of the file names with random words. But we realised teams might think these file names themselves were important to the metapuzzle. So we deliberately chose words so that the first letters of the extra words on all five medals spelt out the phrase "rouge fishy". This was to indicate that this line of thought was a "red herring", and to look elsewhere for the metapuzzle solution.

5. A team who logs in can download large versions of the medals they have won

6. I never received an email with our password. Not that it would have really mattered.

Here's the b*&*h.

Around my house - if we play Trivial Pursuit - we joke that if you don't know the answer. Say either "The King and I" or rosebud as the default answer.

You all did phenomenal!!

j